Valve



O. L. RICE Nov. 2, 1965 VALVE Filed Dec. 28, 1962 lS. HS IIS ATTORNEYS United States Patent Oftce Patented Nov. 2, 1965 3,215,160 VALVE Orval L. Rice, Kalamazoo, Mich., assignor to The New York Air Brake Company, a corporation of New Jersey Filed Dec. 28, 1962, Ser. No. 247,974 2 Claims. (Cl. IS7-596.2)

This invention relates to hydraulic valves of the directional control type.

Valves of this type are frequently used in hydraulic circuits for actuating double-acting motors. In general, the Valve inculdes an inlet passage which is connected with a pump, an exhaust passage which is connected with a reservoir, first and second motor passages which are connected with the opposite sides of the double-acting motor, and a movable valve element which has a neutral or hold position in which each motor passage is isolated from the other three passages, a raise position in which the first motor passage is connected with the inlet passage and the second motor passage is connected with the exhaust passage, and a lower position in which the connections between the motor passages and the inlet and exhaust passages are reversed. In some cases, the movable valve element, or at least that part of it controlling flow to and from the first motor passage, is of the hollow type, i.e., it contains an internal ow passage that forms part of the supply path to the motor in the raise position and part of the exhaust path from the motor in the lower position. This internal flow passage is usually provided with a spring biased check valve that prevents dropping of the load acting on the motor whenever pump supply pressure is below the pressure in the side of the motor that would be contracted by the load.

When circuits of this kind are used to lower large loads, it sometimes happens that the motor moves so fast that its ilow demand exceeds the delivery rate of the pump. This condition causes cavitation in the expanding side of the double-acting motor and obviously is undesirable.

The object of this invention is to provide a directional control valve of the hollow type for actuating a doubleacting motor which reduces the tendency of the motor to cavitate during the lowering operation. According to this invention, the control valve has a lower position in which it connects the expanding side of the motor with the inlet passage and connects the contracting side of that motor with both the inlet passage and the exhaust passage. Flow from the contracting side of the motor to the exhaust passage passes through the check valve in the internal passage in the movable Valve element and this check valve is designed to produce a predetermined back pressure deemed adequate to force fluid into the expanding side of the motor. In this scheme, the expanding side of the motor is supplied with both the iluid delivered by the pump and that portion of the fluid expelled from the contracting side of the motor required to maintain the supply pressure at said predetermined value. The excess fluid returning from the contracting side of the motor is, of course, transmitted to the exhaust passage through the check valve. With this regeneration scheme, the motor lowers the load rapidly while minimizing the risk of cavitation in the expanding side.

The preferred embodiment of the invention is described herein with reference to the accompanying drawing whose single figure is a sectional view `of the improved control valve including, in schematic form, the other circuit components with which it is used.

As shown in the drawing, the control valve comprises a housing 1 having an inlet port 2, an exhaust port 3,

and a through valve bore 4 intersected by seven longitudinally spaced passages defined by annular chambers 5-9, 11 and 12. Annular chambers 7 and 9 are connected with the inlet port 2 by a branched supply passage 13, annular chambers 5, 8 and 12 are connected with exhaust port 3 by manifold 14, and annular chambers 6 and 11 are connected with a pair of motor ports (not shown). Annular chamber 11 has an extension 15 Whose function will be explained later. As in the usual control valve, a relief valve 16 is interposed between supply passage 13 and the manifold 14.

Slidable in bore 4 is a hollow valve member or plunger 17 formed with two annular grooves 18 and 19 that define three valve lands 21, 22 and 23. A pair of axial bores 24 and 25 extend into the plunger from its opposite ends and these bores are closed and sealed by threaded plugs 26 and 27. Axial bore 24 is intersected by two sets of spaced radial passages 28 and 29 and contains a spring biased check valve 31 arranged to prevent flow through bore 24 from passages 28 to passages 29. Axial bore 25 is provided with similar radial passages 32 and 33 and check valve 34, but in this case the spring employed in the check valve exerts a greater closing bias. In a typical case, check valve 34 is designed to open at a pressure differential of about p.s.i. The inner ends of lands 21 and 23 are provided with conical undercuts 36 and 37 which are intersected by radial passages 38 and 39, respectively. Valve plunger 17 is equipped with a centering spring (not shown) that biases it to the illustrated neutral position. Conical undercuts 36 and 37 and radial passages 38 and 39 are provided in accordance with the teachings of Hodgson Reissue Patent 24,580, granted December 23, 1958, for reducing the axial components of the dynamic reaction forces acting on the valve plunger. In addition, undercut 37 and radial passages 39 cooperate with chamber extension 15 to deline the regenerative flow path provided by the present invention.

In operation, inlet port 2 is connected with pump 41 via conduit 42, exhaust port 3 is connected with reservoir 43 via conduit 44, and the motor ports communieating with annular chambers 6 and 11 are connected with the opposite sides of double-acting piston motor 45 via conduits 46 and 47, respectively. When valve plunger 17 is in the illustrated neutral position, lands 21 and 23 isolate annular chambers 6 and 11, respectively, from the other chambers so double-acting motor 45 is hydraulically locked. At this time, pump 41 is unloaded to reservoir 43 along a path comprising conduit 42, inlet port 2, supply passage 13, annular chambers 7 and 9, plunger grooves 18A and 19, annular chamber 8, exhaust manifold 14, exhaust port 3 and conduit 44.

In order to raise the load W, valve plunger 17 is shifted to the left to the raise position in which radial passages 28 and 29 register with annular chambers 5 and 6, respectively, radial passages 32 and 33 register with annular chambers 11 and 9, respectively, and lands 22 and 23 isolate annular chamber 8 from annular chambers 7 and 9 and thus load the pump. Fluid under pressure now flows to the rod end of motor 45 along a path comprising conduit 42, inlet port 2, supply passage 13, annular chamber 9, radial passages 33, axial bore 25, check valve 34, radial paggages 32, annular chamber 11 and conduit 47. Fluid expelled from the head end of motor 45 is returned to reservoir 43 along a path comprising conduit 46, annular chamber 6, radial passages 29, axial bore 24, check Valve 31, radial passages 28, annular chamber 5, exhaust manifold 14, exhaust port 3 and conduit 44. It will be apparent to those skilled in this art that check valve 34 serves to prevent dropping of load W during the time required for pump 41 to build up operating pressure and also at such other times that supply pressure drops below the pressure in the rod end of motor 45. After load W has been moved to the desired position, valve plunger 17 is returned to the neutral position to again hydraulically lock motor 45 and unload pump 41.

Lowering of load W is accomplished by shifting valve plunger 17 to the right to the lower position in which radial passages 2S, 29, 32 and 33 register with annular chambers 6, 7, 12 and 11, respectively, and lands 21 and 22 isolate annular chamber'8 from annular chambers 7 and 9. In this position, the iiuid delivered to supply passage 13 by pump 41 is transmitted to the head end of motor 45 via annular chamber 7, radial passages'29, axial bore 24, check valve 31, radial passages 28, annular chamber 6 and conduit 46. The fluid displaced from the rod end of motor- 45 is delivered to annular chamber 11 through conduit 47, and, if pump 41 is able to supply the demand of motor 45 and, consequently, the supply pressure is higher than the cracking pressure of check valve 34, the return flow from motor 45 is transmitted to the reservoir 43 through radial passages 33, axial bore 25, check valve 34, radial passages 32, annular chamber 12, exhaust manifold 14, exhaust port 3, and conduit l44. On the other hand, if the load W is heavy and tends to move motor 45 at a rate that exceeds the supply capability of pump 41, check valve 34 closes-either partially or completely so that some or all of the iiuid returning to annular chamber 11 passes into supply passage 13 through chamber extension 15, radial passages 39, undercut 37, plunger groove 19 and annular chamber 9. This portion of the return flow, therefore, combineswith the fluid delivered by pump 41 and is led to the head end of motor 45. The spring used in check Valve 34 is so chosen that the back pressure created by this valve always is sufficient to maintain the head end of motor 45 liquid-filled. VIt will be apparent that in those cases where only a portion of the return flow is required for this purpose, check valve 34 opens partially and diverts the balance of that flow to the exhaust manifold 14 and thence to the reservoir 43.

While the load W in the illustrated embodiment acts to contract the rod end of motor 45, in some cases, depending upon the nature of the load and the design ofthe linkages connecting it with motor 45, it may at times act to contract the head end ofthe rn'otor. It is for this reason'that the load drop check valve 31-is included in that portion of the valve plunger 17 that controls the fiow of fiuid to and from the head end of the motor. However, in these cases,it usually is not necessary to provide a regenerative iiow path between the head and rod ends of the motor in the raise position because the effective area of the rod end of motor 45 is much less-than the effective area of the head end and, therefore, the fiow demand imposed on the pump 41 is not as great.

As stated previously, the drawing and description relate only to' the preferred embodiment of the invention. Since many changes can be made in the structure of this embodiment without departing from the inventive concept, the following claims should providethe sole measure of the scope of the invention.

What I claim is:

1. A hydraulic directional control valve comprising v(a) a housing having inlet, exhaust and first and second motor passages;

(b) a movable valve member containing an internal fiow passage and having a first position in which means carried by the valve member and the housing isolate each motor passage from the other three passages, a second position in which means carried by the valve member and the housing connect the first motor passage with the exhaust passage and isolate this motor passage from the inlet passage, connect the second motor passage with the inlet pasage through the internal passage and isolate this motor passage from the exhaust passage, and prevent free communication between the inlet passage and the exhaust passage, and a third position in which means carried by the valve member and the housing connect the second motor passage with the exhaust passage through the internal passage, connect the inlet passage with the first motor passage and prevent free communication between the inlet passage and the exhaust passage, and establish free communication between the second motor passage and the inlet passage; and

(c) a spring biased check valve located in the internal flow passage and arranged to prevent flow from the motor passage toward the inlet passage in the second position and to prevent flow from the exhaust passage toward the motor passage in the third position.

2. A hydraulic directional control valve comprising (a) a housing containing a valve bore intersected by seven longitudinally spaced chambers, there being a central exhaust chamber, first and second outer exhaust chambers located on opposite sides of the central exhaust chamber, first and second motor chambers located, respectively, between the central exhaust chamber and the first and second outer exhaust chambers, and first and second supply chambers located, respectively, between the central exhaust chamber and the first and second motor chambers;

(b) a Valve plunger reciprocable in the valve'bore and containing an internal passage and first and second spaced transverse passages which open through the outer peripheral surface of the valve plunger;

(c) the valve plunger having a first position in which it isolates each motor chamber from the other chambers and connects the supply chambers with the central exhaust chamber, a second position in which the first and second transverse passages register, respectively, with the rst supply and first motor chambers, and means carried by the valveplunger connect the second motor chamber with the second outer exhaust chamber and isolate the central exhaust charnber from the supply chambers, and athird position in which the first and second transverse passages register, respectively, with the first motor chamber and the first outer exhaust chamber, and means carried by the valve plunger connect the second motor chamber with the second supply chamber and isolate the central exhaust chamber from the supply chambers; i

(d) means carried by the valve plungerfor establishing free communication between the first motor vchamber and the first supply chamber in said third position; and

(e) a spring biased check valve located in the internal flow passage and arranged to prevent flow through said passage from the second to the first transverse.

passage.

References Cited hy the Examiner UNITED STATES PATENTS v2,499,425 3/50 Stephens 137-596.12 2,994,346 8/61 Ruhl l37-596.l2 3,008,488 11/61 Vander Kaay et al. 137-596.12

M. CARY NELSON, Primary Examiner.

MARTINP. SCHWADRON, Examiner. 

1. A HYDRAULIC DIRECTIONAL CONTROL VALVE COMPRISING (A) A HOUSING HAVING INLET, EXHAUST AND FIRST AND SECOND MOTOR PASSAGES; (B) A MOVABLE VALVE MEMBER CONTAINING AN INTERNAL FLOW PASSAGE AND HAVING A FIRST POSITION IN WHICH MEANS CARRIED BY THE VALVE MEMBER AND THE HOUSING ISOLATE EACH MOTOR PASSAGE FROM THE OTHER THREE PASSAGES, A SECOND POSITION IN WHICH MEANS CARRIED BY THE VALVE MEMBER AND THE HOUSING CONNECT THE FIRST MOTOR PASSAGE WITH THE EXHAUST PASSAGE AND ISOLATE THIS MOTOR PASSAGE FROM THE INLET PASSAGE, CONNECT THE SECOND MOTOR PASSAGE WITH THE INLET PASSAGE THROUGH THE INTERNAL PASSAGE AND ISOLATE THIS MOTOR PASSAGE FROM THE EXHAUST PASSAGE, AND PREVENT FREE COMMUNICATION BETWEEN THE INLET PASSAGE AND THE EXHAUST PASSAGE, AND A THIRD POSITION IN WHICH MEANS CARRIED BY THE VALVE MEMBER AND THE HOUSING CONNECT THE SECOND MOTOR PASSAGE WITH THE EXHAUST PASSAGE THROUGH THE INTERNAL PASSAGE, CONNECT THE INLET PASSAGE WITH THE FIRST MOTOR PASSAGE AND PREVENT FREE COMMUNICATION BETWEEN THE INLET PASSAGE AND THE EXHAUST PASSAGE, AND ESTABLISH FREE COMMUNICATION BETWEEN THE SECOND MOTOR PASSAGE AND THE INLET PASSAGE; AND (C) A SPRING BIASED CHECK VALVE LOCATED IN THE INTERNAL FLOW PASSAGE AND ARRANGED TO PREVENT FLOW FROM THE MOTOR PASSAGE TOWARD THE INLET PASSAGE IN THE SECOND POSITION AND TO PREVENT FLOW FROM THE EXHAUST PASSAGE TOWARD THE MOTOR PASSAGE IN THE THIRD POSITION. 